Why not 22mbps speed between 802.11b+ & 802.11g?

[GChick]

I recently purchased a USB 2.0 adapter (Dlink DWL G-120 - 802.11g protocol) to use with my Dlink 614+ WAP (802.11b+ protocol). This new adapter replaces a Dlink PCI card (DWL-520+) with which I used to connect at 22mpbs (the boosted speed that comes with 802.11b+ protocol.)

After reading a few articles on the net and some of the posts here, I understand why my USB G adapter transmits only at a much lower speed than what it is capable of. What I don't understand is why is this speed 11mbps instead of the 22mpbs that the WAP is capable of. If the g adapter adapts to the speed that the AP standard can support, shouldn't it be 22mpbs that 802.11b+ can offer? And if yes, any idea what configuration I should tweak to get that?

All wireless hardware on my network are of the Dlink brand. There are no clients with plain standard 802.11b.

Thanks for any input you can send my way.

[GChick]

I got a reply from D-Link support.

REPLY FROM DLINK
You will only be able to communicate between an 802.11g and 802.11b+ device at 11mbps. Both 802.11g and 802.11b+ products use the same modulation (mode of sending the signal) when transferring at 1, 2, 5.5 and 11mbps. When communicating at speeds over 11mbps each wireless standard begins to use a different type of modulation so they are not able to talk to one another when using any speeds over 11mbps. You cannot change the type of modulation the devices use so you will not be able to use any of the speeds over 11mbps.

I was foolishly hoping there would be something 'special' about 802.11b+ to allow a tiny bit more speed but nope. Duh! :rolleyes: Well I guess our next purchase will be a 802.11g WAP. Sometimes down the road.

[wirelessoceans]

Whats up G,

I really wouldn't worry about this too much unless you send massive interoffice documents and files. This is why,

Your internet connection from your ISP is your true "bandwidth". (ie. dsl 1.5 mbps or cable at 3mbps)

Your connection speed from a wireless AP to your wireless client is just the possible data rate between the two devices.

Therefore, if you have dsl at 1.5mbps than you can only transfer data at 1.5mbps, even if you are connected at 22mbps.

Kinda of like driving on a one lane highway with your DSL Car (ISP). Once your hit the Interstate (wireless connection) you still can only use up one lane although there are more lanes avaiable.

So until you get your ISP to give you over 11 mbps of bandwidth. Your wireless connection speed of 802.11b is more than sufficient to deliver the highest possible speed to you.

[Phoenix]

Only products with chipsets inside from Texas Instruments are capable of the 22Mbps PBCC modulation, such as your WAP. Your USB 2.0 adaptor uses a chipset from Conexant that does not support the 22Mbps setting in its hardware.

Realize that while products might have the same brand name on the outside, what's inside two products from a particular manufacturer can be radically different. In most cases, it's the chipset inside (from Conexant, TI, Broadcom, Atheros, etc.) that matters most in the performance of the product, not the OEM (D-Link, Linksys, Netgear, etc.).

[GChick]

Thanks for the clarifications guys. That was VERY useful additional information on top of what Dlink support sent me. :)

It is an irony to have the infrastructure to have more but the available capacity (ISP true speed) forcing us to settle for less. I won't worry about getting an 801.11g WAP right this minute, but I have noticed a slight sluggishness in my connection. Is it my imagination (because I can physically see the indicator about the slower connection) or is it real? LOL, can't say! Perhaps something in the between. But it is something I can live with for now.

Thanks again.

Peace. GC

[Phoenix]

The highest speed your two devices can operate together is 11Mbps.

The WAP supports 1Mbps BPSK, 2Mbps QPSK, 5.5 and 11Mbps CCK (802.11b), and 11 and 22Mbps PBCC (so called 802.11b+) modulations.

The USB adaptor supports 1Mbps BPSK, 2Mbps QPSK, 5.5 and 11Mbps CCK (802.11b), as well as 6, 9, 12, 18, 24, 36, 48, 54Mbps OFDM rates (802.11g).

[GChick]

:cool: Cool! A speed/protocol breakdown. Talk about a crash course in wireless principles.

If only I had that information beforehand. Especially about that DLink DWL-G120 card, I just brought. While I can live with the speed stuck at 11mpbs, I find that connectivity with that adapter can be fickle. I am experiencing the EXACT issues pointed out by Josheph Moran in his Wi-fi Planet review (which I unfortunatley only read today) of this adapter

I am considering returning it to get another brand of USB adapter: another 802.11g or standard 802.11b. After some research on the net I found that USB adapters supporting the enhanced 802.11b+ protocol are rather hard to find. Unless I am looking in the wrong place. Do any of you know of wireless vendors with good variety?

[Phoenix]

Almost all the USB adaptors on the market use the same Conexant chipset that is in your D-Link. A handful use a Taiwanese garbage chipset from Zydas, but I'd stay away from those.